OBJECTIVES: (1) To isolate and determine the structures of the new/novel in vivo active antitumor compounds of selected plant extracts. (2) To investigate the structure-activity relationships of the potent antitumor compounds isolated. (3) To further modify the novel antitumor structures as well as the synthesis of the analogs as an approach to obtain drugs with greater antitumor activity and less toxicity. RESEARCH METHODS: (1) The plant extracts which have been used in folklore remedies for cancer as well as those with reputed biomedical properties in U.S. and Taiwan and elsewhere will be screened for in vivo antitumor activity against P-388 leukemia, Walker 256 carcinosarcoma, as well as Ehrlich ascites carcinoma. (2) Only those in vivo active extracts will be selected as suitable candidates for further chemical studies which include the isolation and structural determination of the active antitumor compounds. Extracts of 18 different plant species in 15 families have been chosen for this purpose. (3) Extraction, fractionation and isolation of the active principles will be guided at every stage by an in vivo antitumor assay in Ehrlich ascites or an in vitro cytotoxicity assay in H.Ep.-2 or KB cells. (4) modern physical methods such as UV, IR, NMR, C-13 NMR, ORD, CD, mass spectroscopy and x-ray crystallographic analysis as well as elemental analysis will be used to elucidate and confirm the complete structures of the active principles isolated. (5) Studies on structure modification in the course of structural elucidation and synthesis of analogs for the active compounds with novel structures will be added in order to investigate the structure-activity relationships as well as possible discovery of new useful antitumor agents. (6) Those compounds which proved to be very active in the in vivo P-388 and Walker 256 screens will be further tested for their effects on L-1210 leukemia, Lewis lung carcinoma and B-16 melanocarcinoma.